From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
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To: | Jeremy Harris <jgh(at)wizmail(dot)org> |
Cc: | "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: regression tests |
Date: | 2013-09-06 18:23:45 |
Message-ID: | CA+TgmoYEOnwDGsi-0b3MBfvkSqUtec+EU7Z5ge8LMb0itaXwbA@mail.gmail.com |
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Lists: | pgsql-hackers |
On Fri, Sep 6, 2013 at 1:34 PM, Jeremy Harris <jgh(at)wizmail(dot)org> wrote:
>> What's an index-hash operation?
>
> Ones that hit tuplesort_begin_index_hash()
Oh. Well, it looks to me like that function can only get called when
building a hash index. Specifically, according to the comment in
hashbuild(), a hash index projected to be larger than shared_buffers.
The regression tests are generally designed to work on small amounts
of data since they need to run quickly, so this isn't too surprising.
Hash indexes are a somewhat underwhelming feature anyway, since btrees
typically perform as well or better, and since hash indexes are not
WAL-logged and therefore can be corrupted on a crash.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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